“He caught his studs in the turf and has damaged his cruciate ligament in his left knee,” he said.

“He’ll have surgery in a week or so’s time, then it is rehab after that. The feeling for this type of injury is around the nine months mark to get back.”

It means the player will be able to take no part in Watford’s promotion push; the Hornets are currently second with 72 points, just one behind leaders Bournemouth but six clear on seventh place Brentford.